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| Rank | Player | Age | Tournament |
|---|---|---|---|
| 1 | 18y 53d | Masters 1985 | |
| 2 | 19y 9d | Masters 1986 | |
| 3 | 19y 76d | ATP Tour World Championships 1993 | |
| 4 | 19y 140d | Masters 1983 | |
| 5 | 19y 176d | Masters 1975 | |
| 6 | 19y 262d | Next Gen ATP Finals 2018 | |
| 7 | 19y 328d | Masters 1978 | |
| 8 | 20y 85d | Next Gen ATP Finals 2018 | |
| 9 | 20y 86d | Masters 1972 | |
| 10 | 20y 92d | ATP Tour World Championships 1991 | |
| 11 | 20y 139d | Masters 1984 | |
| 12 | 20y 162d | Masters Cup 2006 | |
| 13 | 20y 192d | Tour Finals 2023 | |
| 14 | 20y 196d | ATP Tour World Championship 1990 | |
| 15 | 20y 261d | Masters Cup 2001 | |
| 16 | 20y 304d | Tennis Masters Cup 2000 | |
| 17 | 20y 313d | Masters 1980 | |
| 18 | 20y 315d | Masters 1986 | |
| 19 | 20y 326d | Masters 1979 | |
| 20 | 21y 8d | Masters 1988 |